'Over there, on the right!' Stringer shouted.

Inside the Zodiac all heads turned. Not far from the boat some grey whales were diving in glorious close-up. They looked as though they were waving with their flukes. Anawak was busy taking pictures for the archive. Shoemaker would have jumped for joy at the sight of it. It was a picture-perfect trip – as though the whales had decided to make up for their absence by putting on a real performance. Further out to sea three large ones stuck their heads out of the water.

'Those aren't grey whales, are they?' said Delaware, chewing gum.

'Humpbacks.'

'That's what I thought. I don't see any humps, though.'

"There aren't any. They make a hump when they dive, arching their backs in the water.'

'I thought it was because of the lumps on their mouths. Those bumpy things.'

Anawak sighed. 'You're not trying to start another argument, are you?'

'Sorry.' She gesticulated excitedly. 'Hey! Look over there! What are they up to?'

The heads of the three humpbacks had shot up through the surface. Their enormous mouths were wide open, revealing their tongues hanging down from their narrow upper jaws. The baleen plates were clearly visible and the throat grooves looked as if they were straining. A column of water rose up between them, with glints of something that sparkled in the light. Tiny fish, twitching frantically in the air. From out of nowhere flocks of gulls and loons appeared, circled, then plunged down to share the feast.

'They're feeding,' said Anawak, while he photographed the scene.

'Unbelievable! they look like they could eat us.'

'Licia! Try not to make yourself sound dumber than you seem.'

Delaware pushed her gum from one side of her mouth to the other. 'I was joking,' she said. 'I know perfectly well that humpbacks eat krill and other little fish, but this is the first time I've seen them feeding. I thought they just swam with their mouths open.'

'That's how Euhalaena feed – right whales,' said Stringer, turning. 'Humpbacks swim under shoals of fish or copepods and surround them with a net of bubbles. Small organisms don't like turbulent water, so they swim away from the bubbles and cluster together. Then the whales lunge out of the water, expand their throat grooves and start to gulp.'

'Don't try to explain it to her,' said Anawak. 'She knows it all already.'

'To gulp?' echoed Delaware.

Rorqual whales gulp-feed. They expand their throat grooves, which is why they look as though they've been puffed up. As the grooves open up, the throat turns into an enormous pouch, which the whale fills with food. In one huge mouthful the krill and fish are sucked in. The seawater drains out, but the prey is stuck in the baleen.'

Anawak squeezed in next to Stringer. Delaware must have sensed he wanted to talk to her privately because she made her way unsteadily out of the cabin towards the passengers in the front and started to explain gulp-feeding.

After a few moments Anawak asked softly, 'How do they seem to you?'

'Weird question.' Stringer thought about it. 'Same as always, I suppose. How do they seem to you?'

'You think they look normal?'

'Sure. They're putting on a great show, though. In fact, I'd say they're having the time of their lives.'

'So you don't think they've changed?'

She squinted across at them. The sunshine glistened on the water. A mottled grey body rose to the surface, then disappeared again. 'Changed?' she said slowly. 'How do you mean?'

'You know I told you about the megapterae that suddenly appeared either side of the boat^.' At the last second he chose to use the humpbacks' scientific name. What he was thinking was mad, but at least when he put it like that it sounded half-way serious.

'So what?'

'It was weird.'

'That's what you told me. Humpbacks on either side of you. Some people have all the luck – an experience like that, and I missed it.'

'It was like they were checking me out. . . they looked like they were up to something.'

'I don't follow.'

'It wasn't nice.'

'Wasn't nice?' Stringer shook her head in disbelief 'Are you feeling OK? I'd give anything to be so close to them. If only it had been me!'

'You wouldn't say that if you'd been there. You wouldn't have liked it at all. I'm still trying to figure out which of us was watching whom. And why…'

'Leon, they're whales, not spies.'

He passed his hand over his eyes. 'Forget it. I must have been mistaken.'

There was a crackle from Stringer's walkie-talkie. Tom Shoemaker's voice screeched through. 'Susan? Tune into ninety-nine.'

They were currently on ninety-eight, the frequency used by various whale-watching stations to send and receive messages. It was a practical arrangement that allowed them to keep up with all the different sightings. Tofino Air and the coastguards also used the channel, as, regrettably, did various sport fishermen, whose idea of whale-watching was considerably less sophisticated. Each station had its own frequency for private conversations. Stringer switched over.

Is Leon with you?'

'Yes.'

She passed the walkie-talkie to Anawak, who took it and spoke to Shoemaker for a while. Then he said, 'All right, I'll do it. No, it doesn't matter that it's short notice. Tell them I'll fly over as soon as we're back. Catch you later.'

'What was all that about?' asked Stringer, as he handed her the radio.

'A request from Inglewood.'

'The shipping line?'

'Tom had a call from the directorate. They didn't say much except they needed my help and it was urgent. He had the impression they would have liked to beam me over.'

INGLEWOOD HAD SENT A HELICOPTER. Less than two hours after his radio conversation with Shoemaker, Anawak was in the air watching the spectacular landscape of Vancouver Island unfold beneath him. Hills covered with fir trees gave way to rocky mountain peaks connected by shimmering rivers and turquoise lakes. But even the island's beauty couldn't disguise the ravages of logging. The deforestation of vast swathes of land was all too evident.

They left Vancouver Island and flew over the hustling Strait of Georgia. The Rockies, peaks dotted with snow, ran along the horizon, while towers of pink and blue glass lined the sweeping bay, where seaplanes soared and dipped in the air like colourful birds.

The pilot radioed ground control. The helicopter dropped down, banked and headed for the docks. Minutes later they landed. Stacks of cedar towered on either side of them, while mounds of coal and sulphur rose in cubist-style arrangements from the wharf. A colossal cargo vessel was moored nearby. A man detached himself from a group of people and headed over. The wind from the helicopter's rotor ruffled his hair. He was wearing a long coat, and hunched his shoulders against the blast. Anawak unbuckled his seatbelt and made ready to disembark.

The man opened the door for him. He was in his early sixties, tall and well-built, with a round, friendly face and intelligent eyes. He smiled at Anawak and held out his hand. 'Clive Roberts,' he said, 'managing director.'

Anawak followed him to the others, who were inspecting a freighter. They seemed to be a mixture of crew members and people in suits.

They were walking along the starboard side of the boat, staring up at it, pausing, then setting off again.

'It's very good of you to come at such short notice,' said Roberts. 'We wouldn't normally call and expect you to come running, but it was urgent.'

'No problem,' said Anawak. 'What are we looking at?'

'An accident we think.'

'Involving that freighter?'

'Yes, the Barrier Queen. Although it's more to do with the tugboats that were supposed to be bringing her home.'